基于高光谱特征参数的冬小麦氮营养指数估算

为了实现快速高精度获取冬小麦氮营养指数的高光谱监测技术,利用美国SVC HR-1024I型野外光谱辐射仪对2017-2019年关中地区的冬小麦进行遥感监测,获取“三边”参数、任意两波段光谱指数和植被指数,通过相关性分析和逐步回归分析方法筛选冬小麦氮营养指数的敏感光谱参数,结合偏最小二乘回归(PLSR)、随机森林算法(RFR)、支持向量机回归(SVR)和梯度增强回归(GBDT)建立冬小麦氮营养指数模型,并对模型估算精度进行验证。结果表明,从拔节期到灌浆期,各时期的氮营养指数与任意两波段光谱指数均呈极显著相关,其中拔节期氮营养指数与任意两波段光谱指数相关性均高于其他时期,且基于一阶导数光谱的归一化光谱指数和比值光谱指数与氮营养指数的相关系数最大,为0.66。拔节期基于梯度增强回归的冬小麦氮营养指数预测模型的决定系数(r²)和均方根误差(RMSE)分别为0.96和0.05,模型验证的r²、RMSE和相对预测偏差(RPD)分别为0.95、0.12和2.12,模型预测精度最高。因此,拔节期基于梯度增强回归的冬小麦氮营养指数估算模型可用于冬小麦氮营养监测...     

Examining the Impact of Adherence to a Vegan Diet on Acid-Base Balance in Healthy Adults

Acidogenic diets, commonly measured by the potential renal acid load (PRAL), have been linked with metabolic diseases including insulin resistance, hepatic dysfunction, and cardiometabolic risk. Vegan diets are linked to low dietary acid loads, but the degree of adherence to a vegan diet to demonstrate this benefit is unknown. This study compared the change in PRAL and urine pH of omnivores who followed a vegan diet for either 2, 3, or 7 days over one week. Healthy adults were recruited from a campus population and randomly assigned to one of the three groups: VEG7 (vegan diet followed for seven consecutive days); VEG3 (vegan diet followed for three evenly spaced days over one week); or VEG2 (vegan diet followed for two evenly spaced days over one week). Gender, age, and body mass index did not differ between groups (overall: 21.8 ± 2.4 y and 24.4 ± 5.6 kg/m²). Following the one week intervention, outcome measures did not vary between the VEG2 and VEG3 groups, and these groups were collapsed for the final analyses. The 24-h urine pH was raised after seven consistent days of vegan diet adherence and was unchanged after 2–3 days of vegan diet adherence over the course of a week (+0.52 ± 0.69 and ?0.02 ± 0.56 respectively, p = 0.048). However, dietary PRAL scores fell significantly in both dietary groups during the 7-day trial. Since low dietary PRAL scores have been related to improve metabolic parameters, adoption of a vegan diets for several days per week should be explored as a diet strategy to lower disease risk.     

秸秆还田对黄壤农田氮、磷养分平衡的影响

分析2018～2020年不同处理土壤养分、玉米产量、土壤氮磷平衡的差异,筛选出集增产、土壤养分维系及生态环境保护为一体的施肥模式。结果表明,秸秆还田后,土壤有机质、全磷、碱解氮、有效磷含量均有提高,以T4处理(氮、磷减量10%,秸秆还田)最高。秸秆还田增产效果随还田时间增加逐渐明显;T1处理(不施肥、秸秆不还田)经济产量逐年降低,其他处理产量均显著提高。各施肥处理土壤氮素均有盈余,其中,T4处理盈余量随时间增加有下降趋势,T5处理(氮、磷减量30%,秸秆还田)盈余量最低。各施肥处理磷盈余量为165.41～270.16 kg/hm2。相较T2处理(单施化肥),秸秆还田伴随氮、磷化肥减施利于降低环境污染风险。秸秆还田伴随化肥减施能提升土壤养分含量,增加玉米产量,减轻环境污染风险,综合结果显示,T4处理较优。     

有机肥替代对京郊夏播青贮玉米土壤养分动态与平衡的影响

通过田间试验设置4个处理,100%化肥、70%化肥+30%有机肥、40%化肥+60%有机肥和100%有机肥,研究青贮玉米生产中施用有机肥替代化肥对土壤养分动态和平衡的影响。通过测定生育期内表层土壤速效N、P、K养分、土壤微生物量C与N、1 m土体NO_3-含量和青贮玉米N、P、K吸收量发现,在大喇叭口期,有机肥替代化肥处理降低表层土壤无机N的供应水平,提高有效P和速效K的供应水平;在收获期,有机肥替代显著提高土壤微生物量C、N,显著降低81～100 cm土层NO_3-含量和1 m土体NO_3-累积量。有机肥替代提高养分生产力和养分回收量,加剧土壤养分的亏缺。本研究条件下,30%有机肥替代化肥处理土壤N、P、K养分供应水平高,养分回收率高,加剧土壤养分的亏缺,需考虑长期的养分平衡问题。     

Methylmalonic Acid Levels and their Relation with Cobalamin Supplementation in Spanish Vegetarians

Cobalamin deficiency represents a health issue for vegetarians, especially vegans, if supplements are not consumed. Vitamin B12 serum levels, traditionally used to assess the vitamin B12 status, can be normal under functional deficiency conditions. In this regard, methylmalonic acid (MMA) has proven to be a more specific marker to detect subclinical vitamin B12 deficiency. In this study, we present for the first time the cobalamin status of Spanish vegetarians using both vitamin B12 and MMA markers, and the effects of the plant-based diet and the intake of vitamin B12 supplements. Healthy adults were recruited (n?=?103, 52% vegans). Dietary preferences and use of supplements were assessed by questionnaires and serum samples were collected and stored. Vitamin B12 was measured by chemiluminiscence and MMA by liquid chromatography tandem mass spectrometry (LC-MS/MS) using solid phase extraction for sample preparation. Obtained values, median (IQR), were: vitamin B12, 278.9 (160.2) pmol/l and MMA, 140.2 (78.9) nmol/l. No significant differences between lacto-ovo vegetarians and vegans were observed. Considering these two markers, 10% of the participants were mild vitamin B12 deficient. Supplementation (75% of the participants) was associated with higher vitamin B12 (p?<?0.001) and lower MMA (p?=?0.012). In conclusion, Spanish vegetarians have low risk of vitamin B12 deficiency due to vitamin B12 supplementation and the MMA determination is useful to detect mild deficiency.     

玉米平衡施肥对产量、养分平衡系数及肥料利用率的影响

在黑龙江省玉米主产区采用多点田间试验方法研究玉米平衡施肥对产量、养分平衡系数、肥料利用率及农学效率的影响。结果表明,与最佳处理(OPT)相比,3个试验点不施氮、磷、钾、硫、锌、硼肥处理的平均减产率分别为23.9%、9.0%、11.9%、7.0%、7.6%、5.5%。3个试验点OPT处理氮、磷、钾的平均平衡系数分别为0.92、1.06和0.42,说明,150～165 kg/hm2氮素投入、55～82.5 kg/hm2磷素投入略低,养分平衡处于亏缺状态,75 kg/hm2钾素投入过低,养分平衡处于严重亏缺状态。3个试验点OPT处理氮、磷、钾肥平均利用率分别为36.2%、27.3%、46.7%;不施氮肥处理磷肥平均利用率为0.9%;不施磷肥处理氮、钾肥平均利用率分别为20.7%和27.6%;不施钾肥处理氮、磷肥平均利用率分别为23.1%和13.1%,可见,平衡施肥提高了肥料利用率。3个试验点OPT处理氮、磷、钾的农学效率分别为14.1、13.6和15.5 kg/kg。     

沼肥替代部分化肥对杂交水稻产量、土壤肥力及养分表观平衡的影响

通过田间试验,研究沼肥替代部分化肥后对杂交水稻产量、土壤肥力及农田养分表观平衡的影响。结果表明,相比减量施肥处理,随配施沼肥用量的增加,水稻产量呈先升高后下降的趋势;施用沼肥后农田有机质、有效磷、速效钾含量明显增加,氮、磷养分出现盈余,钾素亏缺降低;沼肥用量为16.50 t/hm2时可减少30%的化肥用量。施用沼肥可以减少化肥投入,提高土壤养分含量,维持土壤养分平衡。     

基于图像处理的作物营养诊断研究进展

近年来,随着农业化肥滥用问题的日益突出,图像处理技术在作物营养诊断上的应用研究越来越多。通过对作物营养诊断研究背景的阐述,指出图像处理技术在作物营养诊断上应用的重要意义,介绍作物图像营养诊断研究的总体情况和基本思路,论述作物图像采集、图像预处理、特征提取与优化、分类识别4个环节所用技术方法以及取得的成果,并分析作物图像营养诊断方面存在的问题。     

Annual Nutrient Balance and Soil Chemical Properties in Heavy Multiple Cropping System in the Coastal Area of Southeast Lake Dianchi,Yunnan Province,China

Abstract

To ensure higher yields, farmers in China have increased cropping intensity with a large input of chemical fertilizer and livestock manure since 1980s, which has led to unsustainable agricultural productivity and environmental quality. This study aimed to evaluate the effects of intensive cropping on nutrient absorption and biomass production of crops and to determine the controllable source of residual nutrients in soil in the coastal area of Lake Dianchi, China. Soil and crops were sampled in 32 vegetable fields and four paddy fields; and simultaneously surveyed. In vegetable fields, cropping intensity and input to each crop were extremely high; and, 58, 72, and 20% of nitrogen, phosphorus, and potassium were not absorbed by the crop. Nitrogen absorption ratios of the vegetables were low. The amount of nitrogen absorbed from sources other than chemical fertilizer by vegetables, namely, from soil, manure, or irrigation water, in the fields with three to nine years cultivation duration was higher than those with zero to two years cultivation duration. Reduction of input should be more efficient than enhancing output to decrease soil nitrogen, phosphorus, and potassium; and, reducing input of chemical fertilizer should be more efficient than reducing input of manure. These results should be helpful for reducing agricultural pollution in China.     

High-Resolution Aerial Imaging Based Estimation of Crop Emergence in Potatoes

Plant emergence and stand establishment are key indicators of early crop development that are routinely assessed in potato agronomy and crop improvement research. The standard method for evaluating emergence is through manual plant counts at regular intervals. In this proof-of-concept study, unmanned aerial vehicles integrated with multispectral imaging were used for high-throughput evaluation of crop emergence under field conditions. High-resolution aerial imaging was performed at 15 m above ground level to capture data from potato plots of two varieties (‘Alturas’ and ‘Payette Russet’) in which the seed had been treated with different concentrations of growth regulators (including non-treated controls). The treatments resulted in differences in plant emergence and establishment. The images were collected at 32, 37, and 43 days after planting (DAP). Image-based features such as plant count, SUM-NDVI, and SUM-BINARY were computed from normalized difference vegetation index (NDVI) images for each treatment plot using ArcGIS^®. The Pearson’s correlation coefficients (r) were significant (p < 0.05) between image-based plant counts (r = 0.82) and SUM-NDVI (r = 0.62-0.73) with that of manual plant counts for both varieties, especially at early growth stages (32 DAP) when differences in emergence among treatments were more pronounced. The treatment effects on plant emergence and establishment were effectively resolved in the aerial multispectral images. Selection of the pertinent polygon threshold area to eliminate noise in delineating individual plants during image processing was important for resolution of treatment effects. The data shows that the technique can be applied in potato establishment evaluation.     

土壤主要养分变化和超高产大豆养分吸收之间关系的研究

研究了新疆绿洲生态条件下超高产大豆生育期内土壤中水解氮、速效磷和速效钾3种主要养分的变化情况,并分析了其与大豆主要养分积累之间的关系.结果表明:土壤中水解性氮、速效磷和速效钾每天下降的幅度为: V1～R1期分别为0.29、0.01和0.01 mg·kg-1,R3～R6分别为1.88、0.32和0.14 mg·kg-1,R6～R8分别为2.11、0.23和0.56 mg·kg-1.大豆中后期是土壤主要养分减少的高峰期,大豆整个生育期土壤中水解氮的浓度降低较为明显,速效磷浓度的降低主要集中在大豆生长中期,速效钾浓度的降低则集中在大豆生长后期.水解氮的减少量随着土壤肥力的升高表现出增加的趋势.此外,大豆早浇头水可以提前对主要营养元素的吸收时间,但不改变对主要营养元素的总吸收量.土壤中水解氮的减少和植株体内N的吸收量呈极显著正相关,速效磷、速效钾的减少和植株体内P2O5、K2O的吸收量都呈显著正相关.     

槟榔间作香露兜对土壤养分和养分吸收的影响

为了研究槟榔间作香露兜对土壤养分和养分吸收的影响,采用盆栽试验的方法,对槟榔单作、槟榔间作香露兜和香露兜单作3种种植模式的土壤理化性质和养分吸收进行比较研究。结果表明：槟榔间作香露兜后,相对于单作槟榔,土壤EC值和碱解氮含量显著降低47.15%和25.74%,土壤速效磷含量显著增加32.32%,其中碱解氮与过氧化氢酶和过氧化物酶极显著负相关,速效磷与总根长、根系总表面积、根体积、根数目、脲酶和酸性磷酸酶显著正相关,速效磷与过氧化氢酶和过氧化物酶极显著正相关;槟榔地上部N浓度以及香露兜地上部P和K浓度分别显著增加41.56%、26.56%和25.69%;而槟榔和香露兜根系以及地上部N、P和K养分含量均高于单作,其中根系槟榔P和K含量和香露兜K含量显著增加;同时,间作后槟榔和香露兜对N的吸收效率均高于单作,香露兜的P和K的吸收效率高于单作并略高于槟榔的吸收效率,其中P和K的吸收效率与总根长、总表面积、根体积、根数目均显著正相关,氮的吸收效率与根系形态无显著相关关系。综上所述,槟榔间作香露兜增加了土壤中速效磷含量,促进了槟榔和香露兜对氮、磷和钾养分的吸收,土壤速效磷含量的增加、养分吸收效率的提高均与根系形态显著正相关。     

基于可见光光谱扫描的春玉米氮素营养诊断

采用可见光光谱扫描研究田间条件下春玉米冠层图像色彩参数和氮素营养指标之间的相关性以及简便、快捷、非接触性的作物氮素营养诊断方法。结果表明,春玉米冠层图像色彩参数与氮素营养指标间的相关性依次为6叶期>9叶期>3叶期。在6叶期,春玉米冠层图像色彩参数B、R/G、G/B、G/L、B/L、G/(R+G+B)均与氮素营养指标存在显著或极显著的线性相关关系,其中,G/(R+G+B)与氮素营养指标间的线性正相关性最高。运用可见光光谱扫描的数字图像进行东北地区春玉米氮素营养诊断是可行的,6叶期可作为春玉米氮素营养诊断的关键时期,G/(R+G+B)是春玉米氮素营养诊断的最佳冠层图像色彩参数。     

脲甲醛-石膏-膨润土基大豆缓释肥的研制及其养分释放性能评价

以脲醛-半水石膏-膨润土新型的有机-无机复合缓释材料作为粘结剂,依据大豆的生长需求,采用挤压混合反应-振动筛分-圆盘造粒一体化制备技术,制备出4种低甲醛脲醛-石膏-膨润土基大豆专用的缓释肥料,即缓释氮肥、包膜缓释氮肥、缓释复合肥和包膜缓释肥;采用石英砂连续淋溶法测定缓释肥的养分释放速率,并与常规肥料进行对比,评价大豆缓释肥料N、P、K、S元素的养分释放特性.结果表明:相比常规肥料,大豆缓释肥的养分释放速率缓慢、周期长、缓释性能好,其中包膜缓释肥的缓释性能最好.     

自由空气CO2浓度升高对水稻营养元素吸收和籽粒中营养元素含量的影响

 利用FACE（Free Air Carbon Dioxide Enrichment）平台技术，用水培试验研究了低氮（14 mg/L）和常氮（28 mg/L）水平下，大气CO2浓度升高对水稻（Oryza sativa L.）N、P、K、Ca、Mg、Cu、Zn、Fe、Mn的吸收和在植株不同部位的分配，并着重分析了CO2浓度升高对稻米中营养元素含量的影响。结果表明，按照当前CO2浓度条件下营养元素的正常供应水平，而且各元素都以有效态供给时，CO2浓度升高对多数被测元素吸收总量影响不大，只增加了K、Ca、Fe的吸收总量； N、P、Mg、Mn向穗部分配增加，K、Ca、Cu、Zn、Fe向穗部的分配比例不变；水稻籽粒中P、Ca、Mg、Cu、Zn、Fe和Mn含量无显著影响，N、K含量显著下降。还初步探讨了CO2浓度升高对稻米中人类必需营养元素的不足（或“隐性饥饿”）的影响。     

香蕉果实营养差异及其对人体膳食摄入量贡献评价

为了解不同香蕉品种的营养成分差异及其对人体推荐膳食摄入量(RNI)的贡献,分别以7个海南产香蕉品种的果实为试验材料,通过对糖、酸、维生素C、粗蛋白、矿物质含量等果实品质指标的研究以及香蕉果实营养成分间相关性及变异度的分析,并比较不同品种香蕉果实内含营养对人体营养摄入的贡献。结果表明:不同品种的香蕉果实分别含有5.36%~21.16%的还原糖、15.46%~23.16%的总糖;每百克果实中含有0.20~0.68 g总酸、14.21~34.07 mg维生素C、0.92~1.72 g粗蛋白、262.0~444.3 mg的钾;每千克香蕉果实含0.61~3.51 mg锌、3.79~5.66 mg铁;每百克香蕉可提供膳食推荐摄入量9.5%~14.2%的能量、14.2%~34.1%的维生素C、13.1%~22.2%的钾、2.5%~3.8%的铁以及0.4%~2.3%的锌。通过分析结果表明,不同香蕉品种间的果实营养含量表现出较大的变异幅度,香蕉果实对RNI的部分指标具有较大贡献。     

基于趋势单产和干旱指数的河南省冬小麦单产估算

为了探究相关气象因子对小麦生产的影响,获取极端气候条件下满足精度需求的作物估产模型,以河南省为研究区,对研究区的历史小麦单产数据进行时间序列分解,得到趋势单产,再结合不同时间尺度干旱指数作为输入变量,以实际单产作为输出变量,建立随机森林回归单产估计模型。选择典型干旱年份(2011年)与非干旱年份(2015年)进行小麦单产模型的精度验证,并对输入变量的重要性进行了分析。结果显示,随机森林回归单产估计模型拟合精度整体较高,各市模型的决定系数平均为0.87,平均绝对值误差的均值为17.69 kg·hm~(-2),平均绝对相对误差的均值为0.07。面积加权和简单平均估计得到的各市小麦估产的精度平均值在2011年分别为96.16%和95.12%,在2015年分别为92.99%和92.26%。干旱年份估产精度整体上高于非干旱年份估产精度,面积加权后的小麦单产估计精度略高于简单平均的小麦单产估计精度。对建模贡献最大的输入变量是趋势单产。就干旱指数来说,1个月时间尺度的干旱指数重要性整体高于2和3个月时间尺度的干旱指数;4月份的干旱指数重要性整体高于生长季其他月份的干旱指数。该模型能够准确及时地获取极端气候下小麦产量信息以及变量对小麦产量的影响,可以为研究气候变化对小麦产量的影响和提高极端气候条件下的估产精度提供方法参考。     

茶树养分综合管理与减肥增效技术研究

茶叶产业是我国南方具有比较优势的特色农业和农民增收的支柱产业,但是我国当前茶园施肥中存在较多问题,主要表现为过量施肥、茶树专用肥占比少、有机养分替代率较低和表面撒施等落后施用方法,造成养分损失大、生产成本升高、环境风险增大。针对这些问题,本文从精准养分用量、有机肥替代部分化肥、调整肥料结构、改进施肥方法和配套土壤改良等5个方面总结提出了茶园养分综合管理技术策略,建立了茶园氮素总量控制、磷钾基准配比和用量基准,提出有机肥替代部分化肥的适宜比例与技术,研制茶树专用肥基础配方和稳铵缓释功能性肥料,改进优化追肥时期、深施与机械施肥相结合的施肥方法。茶园养分综合管理技术在农民/合作社生产茶园示范应用过程中节本增效效果显著。     

腐殖酸类营养型改良剂改善火龙果果园土壤理化特性和幼茎养分含量

采用随机区组试验,比较不同施用量腐殖酸类营养型改良剂（2906、4100、5415 kg/hm ²）下火龙果果园土壤理化性状和幼茎养分含量的差异,为火龙果果园的土壤肥力管理提供理论指导。结果表明：虽然腐殖酸类营养型改良剂中化肥用量仅为对照的13.40%、18.90%和24.96%,但改良剂的施用未降低土壤全氮、全磷、全钾和碱解氮、速效磷和速效钾含量,且改良剂施用量为5415 kg/hm ²的处理显著提升了肥沟内土壤速效钾和有机质含量。此外,改良剂的施用未降低土壤pH和火龙果幼茎养分含量。火龙果果园中可施用腐殖酸类营养型改良剂,从而减少化肥的施用量,稳定果园土壤肥力和保障火龙果生长的养分需求。     

基于分数阶微分的春小麦叶绿素含量高光谱估算

为提高农作物叶片叶绿素含量高光谱估算的准确度,以阜康农作物试验地为研究靶区,测定了165个采样点的春小麦叶片叶绿素含量和叶片光谱反射率,运用分数阶微分算法进行光谱预处理,最后运用偏最小二乘法(PLSR)建立叶绿素含量估算模型。结果表明,对数学变换■、lg~R、1/lg~R、1/R)的光谱及原始光谱(R)的数据进行0～2阶分数阶微分预处理时,通过0.01水平显著性检验的波段数量明显增加,且光谱数据经4种数学变换后均在1.2阶微分与小麦叶绿素含量有较高的相关性。1.2阶微分处理后,对叶绿素含量的敏感波段数量表现为■。利用对数变换和1.2阶微分计算的植被指数(NDVI、DVI、RVI、MSR_(705)、MSR_(670,800)、CI)建立的PLSR模型的估算精度最优,其预测的相对误差、决定系数和平方根差分别为2.17、0.87和0.243mg·g~(-1),可作为小麦叶片叶绿素含量的最佳估算模型,也说明对光谱数据进行数学转换和分数阶微分处理可显著提高春小麦叶绿素含量的估算精度。